This invention relates to the field of phonosurgery and, more particularly, to implants, instruments and a method of implantation for surgically medializing a paralyzed or bowed vocal cord.
It is well known that sound is produced in human beings through the passage of air past a pair of vocal cords located in the larynx. Muscles in the larynx operate to vary tension in the vocal cords to regulate them to produce speech and prevent aspiration of foreign particles into the lung.
When one of the vocal cords becomes paralyzed or immobile, voice quality is impaired because tension in the vocal cord cannot be regulated. A controllable tension in the vocal cord or spacing between it and the operable vocal cord cannot be maintained to provide the necessary vibratory sounds required for speech. Vocal cord paralysis can be caused by cancer, trauma or other affliction which would render the vocal cord unable to be tensioned.
It has long been recognized that a paralyzed vocal cord can be repositioned or supported to remain in a fixed location relative to the other operable vocal cord so that unilateral vibration of the other vocal cord can result in acceptable voice patterns. A surgical procedure has been performed through the years by forming an opening in the thyroid cartilage and providing various means for supporting or repositioning the paralyzed vocal cord.
One approach has been to inject "TEFLON" into the paralyzed cord to increase its bulk. This procedure is considered unacceptable because of the inability of the injected "TEFLON" to close large glottic gaps and the tendency of "TEFLON" to induce fibrous reaction. It is also difficult to remove "TEFLON" from the paralyzed vocal cords, if necessary or desirable, at a later date.
A more acceptable approach has been found for supporting the disabled cord, which involves the use of a custom-fitted block of siliconized rubber known as "SILASTIC". The proper size and shape of the block are determined by the operating physician, who hand carves it during the surgical procedure, in order to fine-tune the ability of the patient to phonate or speak. Such blocks have taken the form of wedges which are totally implanted within the thyroid cartilage (see FIG. 3) or flanged plugs that can be moved back and forth in the opening in the thyroid cartilage to fine-tune the voice of the patient (see FIGS. 4 and 5).
Although these implants have proved successful and superior over the "TEFLON" injection method, dissatisfaction has been expressed because the surgical procedure requires too much time, either through custom sizing of an implant, difficulty in inserting the implant or lack of efficient method of locking the implant in place. This is a drawback because in order for a patient's voice to be fine-tuned, the patient must be kept under local anesthesia so he or she can produce sounds to test the positioning of the implant.
While being operated upon, the patient can only phonate a limited period of time so that the longer the operation and the more times the patient's voice has to be tested, the less likely that the patient's voice can be fine tuned to its optimum level. Vocal cord edema, due to a prolonged procedure, also interferes with an optimal surgical result. Therefore, there exists a need for an implant which can quickly and simply be sized and manipulated so it can be located in the proper position relative to the paralyzed vocal cord for fine tuning a patient's voice.